(a) Technical Field
The present invention relates to a sound absorbing and insulating material and a method for manufacturing the same. In particular, the present invention provides a sound absorbing and insulating material and a method of preparing the same by impregnating a polyimide binder into a nonwoven fabric formed of a heat-resistant fiber. The thus prepared sound absorbing and insulating material may obtain superior sound-absorbing property, flame retardancy, heat resistance and heat resistance and moldability. The sound absorbing and insulating material of the present invention may suitably be applied to a part at which a temperature from room temperature to about 300° C. may be maintained.
(b) Background Art
Noise is an unwanted side effect of industrial development and causes gradually more damages. Accordingly, various methods have been provided to prevent noise. As a way of such noise prevention, researches for developing new sound absorbing and insulating materials capable of arresting, absorbing or insulating sound have been conducted in various ways.
Representative industrial sectors requiring sound absorbing and insulating materials include electric appliances such as an air conditioner, a refrigerator, a washing machine, a lawn mower, and the like, transportation such as a vehicle, a ship, an airplane, and the like, construction materials such as a wall material, a flooring material, and the like, and so forth. The sound absorbing and insulating material may also be required in other various industrial fields. In general, the sound absorbing and insulating materials used in industries may require, in addition to good sound-absorbing property, reduced weight, flame retardancy, heat resistance and heat-insulating property, depending on their applications. Particularly, flame retardancy and heat resistance may be additionally required for sound absorbing and insulating materials, particularly when they are used in engines, exhaust systems, and the like where high temperature of 300° C. or greater is maintained. For example, an aramid fiber, a polyimide fiber and an oxidized polyacrylonitrile (oxi-PAN) fiber have been used for sound absorbing and insulating materials with superior heat resistance.
In addition, in order to provide functionalities such as flame retardancy, water repellency, and the like to a sound absorbing and insulating material, many sound absorbing materials made of a nonwoven fabric containing aramid fibers and a functional skin material may be stacked.
For example, Korean Patent Publication No. 2007-0033310 discloses a flame-retardant sound absorbing material wherein a nonwoven fabric layer in which a heat-resistant short aramid fiber and a short thermoplastic polyester fiber are bridged and a skin material layer formed of a wetlaid nonwoven fabric consisting of a short aramid fiber are stacked.
In addition, Japanese Patent Publication No. 2007-0039826 discloses a water-repellent sound absorbing material wherein a nonwoven fabric layer of a heat-resistant short aramid fiber or a blend of a short aramid fiber and a short thermoplastic polyester fiber and a skin material layer treated with a water repellent are stacked.
Further, Japanese Patent Publication No. 2007-0138953 discloses a heat-resistant sound absorbing material wherein a nonwoven fabric layer consisting of a heat-resistant aramid fiber and a skin material layer formed of a fiber sheet containing a heat-resistant aramid fiber are stacked.
However, because the sound absorbing materials described above have a structure wherein a skin material layer is laminated on one side of a nonwoven fabric to provide functionalities such as flame retardancy, water repellency and the like, a hot pressing process for integrating the nonwoven fabric layer and the skin material layer may be necessary. Consequently, the overall process is complicated and troublesome, and a flame retardant, a water repellent, and the like included as additives may produce toxic gases as a result of combustion during the hot pressing process. In addition, deformation of the internal structure of the nonwoven fabric that may occur during the hot pressing process can lead to deterioration of sound-absorbing property.
The description provided above as a related art of the present invention is just merely for helping understanding of the background of the present invention and should not be construed as being included in the related art known by those skilled in the art.